Page 13 - Contractors World -UK & Ireland Vol 2 No 4 (May 2012)

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Page 13
Contractors World - UK & Ireland Vol 2 No 4
month which is required ahead of works to widen and deepen the
central section of the Connaught Tunnel so it can accommodate
Crossrail’s larger trains.
The water table is also being lowered to allow for the pump
house shaft to be deepened by another seven metres to 25 metres
in order for it to accommodate modern pumping equipment that
will work to keep the tunnel dry.
Th i s att rac t i ve Vi c tor i an pump house i s too sma l l to
accommodate the larger modern pumping equipment to be installed
as part of the tunnel’s major refurbishment.
So, during the coming weeks the 130 year old pump house will
be removed brick by brick and will be donated to Newham Council.
The SS Robin is one of the world’s oldest steamships and was built
in east London. The ship’s trust is seeking a permanent berth in the Royal Docks and it is proposed the pump house
structure would form the quayside ticket office.
Demolition of the former North London Line station at Silvertown is commencing.
Works in Connaught Tunnel are well underway with the ballast and rail tracks already removed. Major piling works
are also underway at the western approach to the tunnel in order to strengthen the ground. Survey work to identify
potential unexploded ordnance from World War II has been completed in the tunnel’s western approach with the all clear
given. Crossrail’s archaeologists have opened their fourth and final trench for the site, searching for possible evidence of
human activity dating back 6,000 years.
Connaught Tunnel Project Manager Linda Miller said, “Works are progressing extremely well and we are on track
for turning this Victorian railway tunnel into modern infrastructure that will service London well into the next century.
Major works will begin early next year after the London Boat Show, which will include placing coffer dams in the passage
between Royal Victoria and Royal Albert docks, pumping out the water and performing engineering open heart surgery
to widen and deepen the central section of the tunnel.”
The Connaught Tunnel in the Royal Docks was built in 1878 and was part of the North London Line until 2006. The
tunnel will be extensively refurbished as part of works to construct Crossrail’s new Abbey Wood branch.
Sections of the existing tunnel are in a poor structural condition. In 1935, larger ships began scraping the bottom of
the Royal Victoria Dock which sits above the tunnel. As part of work to deepen the dock, the central section of the tunnel
was narrowed with brickwork removed and steel segments installed.
Change of plan
Crossrail originally planned to strengthen the central section of the tunnel by removing the existing steel linings and back
filling the entire section with concrete foam.
These tunnels would then have been enlarged by boring through the concrete to create tunnels large enough for
Crossrail trains to pass.
However, concerns about the structural integrity of the tunnel as a result of work in the 1930s to narrow the tunnel
have led to a new approach which will involve workers digging down to the tunnel to undertake the enlargement work.
This will be the first time the tunnel has been exposed from above ground since its construction in the 1870s.
Refurbishment of the Connaught Tunnel is being undertaken by Vinci Construction UK Ltd.